The owner of the current invention is also the owner of a number of previous patents for couplings used to interconnect confronting ends of fluid carrying conduits in an aircraft. These patents include the U.S. Pat. Nos. 5,871,239; 6,050,609; and 6,073,973. Characteristics common to each of the inventions disclosed in these patents are coupling devices that include a plurality of threaded members which are rotatable in a locking direction, and rotatable in an opposite unlocking direction. Locking of the couplings is achieved by locking tabs that are received in corresponding notches/reliefs. A resilient member is provided to ensure that the couplings remain in a locked position when the coupling is tightened to a predetermined extent during rotation in a locking direction. Visual indicia is provided to indicate when the couplings have been placed into locking engagement.
Nadsady U.S. Pat. No. 3,669,472; Gale et al. U.S. Pat. No. 4,808,117 and Gale et al. U.S. Pat. No. 4,928,202 each disclose a coupling device in which the tightening of the coupling parts is readily accomplished, but accidental loosening is restrained by spring fingers carried by one of the coupling parts which engage indentations or notches on the other coupling part in such a manner as to favor relative rotation of the coupling parts in the tightening direction, while restraining with greater force the rotation of the coupling parts in the opposite unlocking direction.
Cannon U.S. Pat. No. 3,999,825; Filippi U.S. Pat. No. 4,008,937; Mahoff U.S. Pat. No. 4,249,786 and Gale U.S. Pat. No. 4,346,428 each disclose a coupling with one or more toggle latches which snap into a positive locking position.
Spinner U.S. Pat. No. 4,285,564 discloses a coaxial plug connector wherein a first ring of axially pointed teeth is provided around the circumference of a cap ring. A first connector has a ring with teeth for engaging the teeth on the cap ring. The cap ring is withdrawn axially against the force of a biasing spring when the coupling is rotated to a different position. The cap ring is released and the spring urges it into locking engagement with the tooth ring. Thus, accidental rotation of the cap ring relative to the first connector is prevented.
Runkles et al. U.S. Pat. No. 4,881,760 discloses a coupling with locking tines having visible indicia for determining whether or not the tines are in locked position.
Runkles et al. U.S. Pat. No. 4,900,070 discloses a coupling with spring biased rotatable locking tines.
Many prior art coupling devices are specifically designed so that the couplings are able to maintain a fluid tight connection between the conduits even when the joined conduits are misaligned. These couplings typically use multiple sealing members or o-rings in at least two or more coupling components to provide some amount of resiliency in the coupling allowing misalignment. For couplings used in aircraft applications, this misalignment can be caused by live loading conditions wherein vibrations from the aircraft and other forces cause periodic shifting of the conduit members. This misalignment can also be caused by static forces, such as may be attributed to the particular orientation of the conduit members when they are assembled in the aircraft.
In the construction of an aircraft, there are constraints in available spaces to run conduits for hydraulic and electrical lines. In such constrained spaces, it is very difficult to provide the necessary support brackets to support the conduits. More particularly, when it is necessary to make a connection between confronting ends of conduit members, the constrained spaces make it even more difficult to install the couplings and to provide support brackets near the couplings. Although many couplings as mentioned above have the capability to provide a sealed connection with misaligned conduits, misalignment is avoided in most all aircraft applications as a safety precaution to prevent fuel leakage for fuel lines.
Therefore, there is a need for a rigid connection that can be established between confronting conduit members thereby eliminating the need for further structural support to join the conduit members, yet the connection should be lightweight, capable of transmitting shear loads between the conduit members, and of a small enough size that the coupling can fit within the constrained spaces. Additionally, it is highly advantageous to provide electrical continuity between the interconnected conduits. Electrical continuity ensures that there will not be a buildup of an electrostatic charge on a first conduit relative to the second interconnected adjacent conduit. As a result, there is no potential difference between joined conduits or between a conduit and another reference surface, thereby eliminating the creation of an electrical spark that otherwise could ignite vaporized fuel present in the conduit members.